setTransformation

Sets the internal transformation of the element, that is, the
transformation that converts the standard XYZ axes to the body's
internal reference axes.
The transformation is copied and cannot be accessed by users
directy. This implies that changing the original transformation
has no effect on the element unless a new setTransformation() is invoked.
The transformation uses the body's position as its origin.

toBodyFrame

This method converts a double[3] vector from the space's frame to
the body's frame.
This only works properly if the internal transformation is not set
(i.e. it is the identity) or if it is invertible.
Otherwise, a call to this method will throw an
UnsupportedOperationException exception.